1. Field of the Invention
This invention relates to a semiconductor device and a method of manufacturing the same, and more particularly to a semiconductor device having an element wiring layer wiring beneath a bump connected to a rewiring layer wiring.
2. Description of the Related Art
A conventional structure beneath a bump has a metallic film having a larger area than its bonding area to the bump (For example, see Japanese Patent Publication No. Hei-1-120040).
Now referring to FIG. 5, an explanation will be given of an uppermost layer element wiring structure beneath a bump connected to a rewiring layer wiring of a conventional semiconductor device. FIG. 5 is a main-part enlarged view of an example of the uppermost layer element wiring structure beneath the bump connected to the rewiring layer wiring.
An uppermost layer wiring (also referred to as an element wiring) 102 above a semiconductor substrate 101 with a desired element region is covered with a protection film 103. An insulating film 104 is formed on the protection film 103. The insulating film 104 beneath a bump 105 is selectively removed. On the insulating film 104, a rewiring layer 106 is wired. Beneath the bump 105, a metallic film 107 is formed which connects the rewiring layer 106 and the bump 105.
In many cases, the uppermost layer wiring 102 has a narrower width than a connecting area between the bump 105 and the rewiring layer 106.
In this way, since there is the element wiring 102 having a narrower than the connecting area between the bump 105 and rewiring layer 106, a level difference or step will be formed at the portion corresponding to the edge of the element wiring 102 so that the protection film located at the step may be thin and fragile owing to the stress applied to the edge.
Further, an unevenness is formed on the surface of the protection film 103 and the rewiring layer 106 is formed on the uneven surface. In this case, the stress is concentrated on the edge of the unevenness so that the protection film 103 may be broken.
The bump having a large thickness is formed on the rewiring layer 106 so that greater stress is applied to the protection film. Further, since a high temperature occurs not only during the film deposition of the bump but also its using, i.e. connection of the semiconductor device to a printed board through the bump is made at a high temperature, the protection film is likely to deteriorate owing to further stress and heat.
Owing to the causes described above, the rewiring layer 106 and the element wiring 102 may be short-circuited owing to the step at the edge of the element wiring 102.
This invention has been accomplished under the above circumstance. An object of this invention is to provide a semiconductor device which can prevent an uppermost layer wiring and a rewiring from being short-circuited beneath a bump and is free from short-circuiting failure.